Table 6.

Regression results comparing the change in cognitive outcome (follow-up minus baseline) between those who increased their MP (or CP) calls weekly from baseline to follow-up, and those who did not increase or reduce their MP (or CP) usage

	Difference in cognitive outcome means between those who increased MP (or CP) use and those did not increase or reduc their use
	Voice calls on MP			Voice calls on CP
Tests	Parameters	Estimate	95% CI	Estimate	95% CI
Detection task	Response time (ms)a	−0.008	−0.042, 0.027	0.007	−0.019, 0.033
	Accuracy (%)b	0.024	−0.036, 0.084	−0.069	−0.127, −0.012
Identification task	Response time (ms)a	−0.008	−0.034, 0.018	0.007	−0.011, 0.024
	Accuracy (%)b	0.012	−0.044, 0.067	−0.047	−0.097, 0.002
One-back memory task (Working memory)	Response time (ms)a	0.009	−0.018, 0.036	0.017	−0.006, 0.041
	Accuracy (%)b	0.014	−0.048, 0.076	−0.029	−0.077, 0.019
One card learning task (Visual recognition memory & attention)	Response time (ms)a	0.005	−0.033, 0.043	−0.0008	−0.034, 0.032
	Accuracy (%)b	−0.022	−0.054, 0.009	−0.011	−0.049, 0.026
Go/NoGo (Response inhibition task)	Response time (ms)a	−0.030	−0.054, −0.006	0.009	−0.013, 0.032
	Accuracy (%)b	0.011	−0.037, 0.059	−0.013	−0.060, 0.034
Groton maze learning task	Accuracy (total no. of errors)	6.22	2.13, 10.31	−2.77	−8.77, 3.24
Time ratio ((B-A)/A)	Response time (s)	0.056	0.021, 0.090	−0.028	−0.069, 0.013
Time ratio ((D-C)/C)	Response time (s)	−0.048	−0.127, 0.033	−0.003	−0.066, 0.059

Reference group: no change or decrease in total average number of MP or CP calls weekly (exposure dichotomized: “no change or decrease” and “increase” in total average number of MP and CP voice calls weekly)

Adjusted for age at baseline, sex, ethnicity, SES (classified into quintiles), lag time between baseline and follow-up, handedness, and total screen time weekly (gaming and computer/Internet use)

The bold numbers represent significant assoctions

^alog₁₀ transformed data, ^bArcsine transformed hit rate